Process of producing barium oxid



J. B. PIERCE. JR. PROCESS 0F PHUDUCING BARIUM OXID.

APPLICATION FILED NAYS. IEIIB.

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JAMES B. PIERCE, JR., OF CHARLESTON, WEST VIRGINIA.

PROCESS OF PRODUCING BARIUM OXID.

Specification of Letters Patent.

Patented June 3, 1919.

Application tiled May 6, 1918. Serial No. 232,902.

To all `whom it may conccm.'

Be it known that I, JAMES B. PIERCE, Jr., a citizen of the UnitedStates, residing at Charleston, in the County of Kanawha and State oflest yirginia, have invented certain new and useful Improvements inProcesses of Producing Barnim Oxid, of which the following is aspecification.

My invention relates toa process of producing from barium carbonate,barium oxid` suitable for oxidation into high test barium pcroxid.

It is well known, that barium oxid can be produced from bariumcarbonate, but the barium oxid thus produced is not capable of being'oxidized into barium peroxid of high test, to wit, over 88 per cent.Ba02.

As a result of this inability of the barium oxid prodined by thc wellknown processes, to be converted into a high test barium peroxid, thebarium oxid produced at the present time is generally made from bariumnitrate.

In accordance with prior processes, it has been customary to mix bariumcarbonate with carbon or other reducing agent, and then heat the mass toa temperature varying from 10000 C. to 1200O C. It was heretoforecustomary to heat the mass in a hermetically sealed crucible, and thisheating was carried out in an atmosphere of carbon monoxid. In somecases, the barium carbonate and carbon or other reducing agent were madeinto briquets. It was also necessary to withdraw the gases as formedfrom the sealed Crucible or reaction chamber and this withdrawal ofgases was continued to the point of creating a vacuum. It was alsocustomary to mix other ingredients with the barium carbonate and carbon,such as barium nitrate, calcium oxid, barium peroxid, ete.

The above referred to processes have not proven Wholly satisfactory,inasmuch as the barium oxid obtained is not porous, and is accordinglyincapable of oxidation into barium peroxid of a high test, to wit, over88 per cent. BaO,. Barium oxid obtained by the processes above referredto is a hard, extremely dense mass, incapable of oxidation, or capableof oxidation to only a slight extent.

This hard and extremely dense character of theY barium oxid thusobtainedis due to the formation of a fusible basic barium carbonate. Thefusing point of barium carbonate is 1380O C. and its dezomposition intobarium oxid may be effected in the presence of glowing carbon at atemperature of about 1150O C. There is produced in this process, adouble compound, probably having thc approximate composition Ba.BaCOThis compound is the fusible basic barium carbonate above referred to,and it has a fusing point below 1050C C. It is thus seen that the basicbarium carbonate (BaO.BaCO3) will fuse before or duriingr thedecomposition of the barium carbonate into barium oxid and carbondioxid.

Furthermore, it has heretofore been impossible, in operating' undercommercial units, to hare the barium carbonate and carbon absolutelydry. there results within the crucible water vapor` which in turn causesthe formation oi' another iompound, having ap Jroximatcly thecomposition BatOI'DZBaClOg, whose fusing point is slightly lower thanthat of the basic barium carbonate. The fusing" point of the last namedcomposition is about 950O C. to 1000O C.

As a result of the practice of the process above referred to, whereinthe barium carbonate is heated in the presence of carbon, particles ofunburned carbon or other reducing agent, remain disseminated throughoutthe mass of barium oxid produced. These particles of carbon are inclosedand coated over by the fused or semi-fused reaction mass, which preventsthe carbon from either reacting with the oxygen of the barium carbonate,or burning to carbon monoxid or carbon dioxid, by contacting with thehot atmosphere of the crucible. The presence of the line particles ofcarbon iu the barum oxid produced, effects two marked disadvantages.During the oxidation process of the barium oxid, to produce the bariumperoxid, the carbon should be largely converted into carbon dioxid, if ahigh test barium peroxid is to result. However, this carbon dioxidreacts with the unoxidized barium oxid, reverting it to the bariumcarbonate. Secondly, the carbon particles which do not react in thisway, remain in the barium oxid, thereby imparting to it a gray color.This color persists through the blanc fixe when the barium peroxid isused, in the manufacture of hydrogen peroxid. It is obvious that thepresence of the carbon particles, in the barium oxid is a seriousdrawback.

Vhen the mixture of barium carbonate and carbon are heated as aboveindicated, llie burning or oxidation of the carbon, or other reducingagent, takes place over the outer surface or wall of the mass, towardthe center thereof. 1t is found if the reaction crucible be opened andthe mass of barium carbonate and carbon examined, after said mass hasbeen heated for only a. short time, and before the temperature has risento the point where the barium oxid is produced, that iii the outer wallsor surface of the mass, and extending into the mass for a substantialdepth, the carbon will have burned away, leaving only barium carbonate.This will be the case whether the reaction mass of barium carbonate andcarbon be charged into a cold reaction retort or a retort heated to anydegree up to and including the temperature of the reaction. The reactionmass will therefore consist of two compositions, to wit, bariumcarbonate, and a mixture of barium can bonate and carbon. 'hen thereaction ieiiipcrature required for the formation of barium oxid frombarium carbonate in the presence of glowing carbon, is reached, thebarium oXid will be formed from the coinposiiion containingl thc bariumcarbonate and carbon. This barium oXid thus produced will react with thebarium carbonate present upon the outer portion of'the mass but beingfree from carbon, thereby forming basic barium carbonate, BaQBaGOS. Thisbasicl barium carbonate fuses at a low temperature, as above indicated.

The presence of strontium carbonate in all commercial barium carbonate,further prevents the production of barium oxid capable of oxidation intoa high test barium peroxid. The eti'ect of the strontium carbonate` inthe production of barium oxid from heating barium carbonate in thepresence of carbon, is to form an easily fusible compound, probably ofthe composition SrtlBaCOs. This composition is formed, as strontiumcarbonate decoinposes in the presence of glowing carbon at about105000., forming S1O.BaCO3. It requires a further 1500 C. oftemperature, to wit, 1200O C. to e'ect the decomposition of the bariumcai bonate. r

An important object of my invention is to Jroduce from barium carbonateporous barium oXid, capable of oxidation intov a high test bariumperoXid.

In the accompanying drawings, forming" a part of this specification andin which like numerals are employed to designate like parts throughoutthe same,

Figurel is an end elevationof an apparatus employed in the practice ofmy process, and i Fig. 2 is a vertical longitudinal section taken online 2--2 of Fig. 1.

In the drawings, the numeral 5 designates the outer casing of thefurnace, which mayr be forn'ied of iron, and is preferably cyliiidrical.This casing is lined with refmctoryr material 5. The casing 5 isprovided at its opposite ends with annular fianges (i, to which arebolted, as shown at. T, heads or ends 8 and E). The heads are providedcen trally thereof with openings l0, covered by doors 11, which areclamped or bolted to the heads, as shown at 12. These doors engagecopper packing 13, thereby forming a fas tight joint.

1`he numeral 11 designates a reaction chamber or inutile, preferablyarranged concentric within the casing 5. The reaction chamber 14 has itsforward end open while its opposite end is closed by a head 15. Thisreaction chamber is formed of refractory material. Surrounding thereaction chamber 1l in spaced concentric relation is an outercylindrical casing 1G, formed of rcfractory material. A ring 1T ofrefractory material, is arranged between the forward ends of thereaction chamber ll and casing 1G, while a` head 1S of refractorymaterial is arranged within the opposite end oi' the casing 10, asshown.

The numeral 19 designates current dis tributino' 'rings arranged betweenthe reaction chamber 14 and easing 16, and preferably formed ofgraphite. (,oiiiiected with the current distributing rings 19 areelectrodes 20, preferably formed of graphite and extending throughopenings 211 formed in the heads 8 and 9, but haring no electricalcontact therewith. The electrodes Z0 pass through stutling-boxes 22,formed of insulat ing material, which also aiford a gas tight joint. Theelectrodes Q0 are, of course, connected with the opposite poles of asource or' current. The nun'ieral 23 designates an air nular resistorconfined between the reaction chamber 1i and the casing 10, andcontacting at its opposite ends with the current distributing rings 19.This resistor pret'- erably formed of granular carbon or other suitablematerial, and the same preferably has the same density throughout itsmass thereby insuring a uniform heating of the reaction chamber.

Leading into the outer casing 5 is a pipe 211, having a transverse pipe25 connected therewith. 27. The end 2G is adapted, for connection with apressure pump, to supply compressed gases into the casing 5, While theend 27 is adapted for connection with a vacuum pump to withdraw gasesfrom Within the casing 5 and` create a substantial degree of vacuumtherein. Valves Q8 and 29 are connected in the pipe 25, inwardly of theends 26 and 27.

In the practice of my process, in connection with the apparatus herewithshown and described, the reaction chamber 14 is first heated to atemperature of about 1000o C.

The pipe 25 has ends 2G and lit but not exceeding the Same, at whichtemperature it ischarged with the barium carbonate, which is preferablyof a pure va riety. After the reaction chamber 13 is thus charged,the'door 11 in the head 8 is returned to its closed osition to form a astight union with the -ead 8. This heating operation is continued untilthecharge of barium carbonate reaches a temperature of approximately10900 C., at which time the casing 5 is evacuated, preferably to Q5 or26 inches of mercury. This is effected by opening the valve 29 with thevacuum pump in operation. This evacuation is continued for a `fewminutes, about five to ten m1nutes, until the small amount of Water ormoisture, which is alwa s present in barium carbonate and retaine by ituntil heated to a red heat, has been expelled from the barium carbonateand Withdrawn from its presence and from the furnace. The valve 29 isnow closed, and the valve 28 is opened, in order that a change of carbondioxid or a gaseous mixture containing carbon dioxid, nitrogen andoxygen is supplied into the casing 5, through the valve 28, and underpressure. The gas or gases fed into the casing 5 and subsequently intothe reaction chamber 14 is under sufficient pressure to prevent thedecomposition of any strontium carbonate which is present in the bariumncarbonate, at the temperature of 1300o C. It has been found that aboutten pounds to the square inchki-'s asuitable pressure for this purpose;Th current is now continued through the resistor 23 until a temperatureVof 12500 C. to 13000 C. is

reached, when the furnace is evacuated Aas rapidly as possible, which isaccomplished by closing the valve 28 and opening the valve 29. As high adegree of vacuum is produced in the casing 5 as possible, preferablyfrom one to two inches of mercury, or approaching the zero absolute asmuch as possible. This vacuum is maintained during the decomposition ofthe barium carbonate.

With the barium carbonate heated Within the furnace to a temperature of12500 C. to 13000 C. and subjected to the action of a high degree ofvacuum, as above stated, the barium carbonate will decompose into bariumoXid and carbon dioxid according to the following reaction:

BaCO3=BaO+CO2.

The decomposition of the strontium carbonate is prevented in thepreliminary stages of the heating (10000 C. to 12000 C.) by maintainingWithin the reaction chamber a partial pressure of carbon dioxidsuiiicient to prevent the decomposition of strontium carbonate at 12500C. When the tcmpcrature of 12500 C. is reached the chamber is rapidly'evacuated to as near zero absolute as possible. When this is done boththe barium carbonate and strontium carbonate decompose simultaneously,but under the above conditions of temperature and pressure, the velocitof the reaction of decomposition of barium carbonate into barium oxidand carbon dioxid is suiiiciently great and approaches sufficiently thereaction velocity of the decomposition of strontium carbonate intostrontium oxid and carbon dioxid that the decomposition of both bariumcarbonate and strontium carbonate is simultaneous through the mass thusaffording no opportunity for interaction between any of the constituentswithin the mass which would lead to the formation of fusible compoundsas set forth in the speciication.

By the employment of the particular furnace the mass of barium carbonateis uni' formly heated throughout, whereby the basic barium carbonate 1snot produced. The velocity of the reaction, under-the conditions oftemperature and pressure specified, is sufliciently rapid to prevent theformation of fusible compounds. I am thereby able to produce a porousbarium oxid, capable o oxidation into a high test barium peroxid.

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a preferred example of the same and thatvarious changes may be resorted to in the steps of the process withoutdeparting from the spirit of the invention orfthescope of the subjoinedclaims.

Having thus described my invention, I claim: Y

`f1.`Tlie herein described process of producing a porous barium oxidcapable of oxidization into a high test barium peroxid, Which consistsin heating a mass of barium carbonate in the presence of a suitabledegree of vacuum to separate out the Water contained therein from thebarium carbonate, subjecting the barium carbonate thus treated to theaction of a gaseous pressure exceeding atmospheric pressure Whileincreasing the degree of heat applied thereto until the reactiontemperature of the barium carbonate is approached, and subjecting thebarium carbonate While heated to the reaction temperature to asubstantial degree of vacuum whereby the barium carbonate is decomposedinto barium oXid and carbon dioxid.

2. The herein described process of producing a porous barium oxidcapable of oxidization into a high test barium peroxid, which consistsin heating commercial barium carbonate containing strontium carbonate inthe presence of a suitable degree of vacuum to separate out the Watertherefrom,.subject ing the mass thus treated to the action of a gaseouspressure at a suitable degree to prevent the decomposition of thestrontium carbonate when the temperature of the mass is raised toapproach thedecomposition temperature of t e barium carbonate,increasing the degree of heat applied to the mass While subjected tothegaseous pressure until the reaction temperature of the barium carbon151water-to remove therefrom,all` substantial traces of water, heatingthe mass to the reac tion temperature of the barium carbonate whilesubjecting itto the action of gaseous pressure for preventing thedecomposition of the-strontium carbonate prior to the decomposition ofthe barium carbonate, and sub jectingr the mass to the action of asubstantial degree of vacuum when the reaction temperature of the bariumcarbonate is ap- 2 5 preached.

11. The herein described process of produc ing a porous barium oxidcapable of oxidization into a high test barium peroxid, Which comprisesas u subcombination, the heating of commercial barium carbonate tothereaction temperature in the presence of a substantially high degree ofvacuum and in the absence of a reducing agent.

5. The herein-described process of pro-` S 5 ducingr a porous bariumoXid .capable of oXi-l 6. The herein described process of pro ducingbariumoxid from barium carbonate, which consists in heating the bariumcarbonate free from a reducing agent to a reaction temperature intherpresenceiofsa'high degree offivaeuun'hK t Hifi l mi, k

,ma wy il i 117. :The hereindescribedprocess of produc` i mg bariumoxidrifrom, barium carbonategi which consists iniremoringfrom theVbarium carbonate'ahi'substantal 4trraces of Water, and heatingthe bariumcarbonate free, from a reducing agent to'a reaction temperature in thepresence ofahighfdegree of vacuum.

8. The herein described process of producing"l barium oxidr-:frolnbarium carbonate, which consists inheating the barium carbonatecontaining strontium carbonate to a reaction temperatureof the bariumcarbonate andpreventing the decomposition of the strontium carbonate,and then rapidly effecting the decomposition of barium carbonate forproducing the barium oXid Without the formation of any fusiblecompounds.

In testimony whereof I aiiix my signature in presence of tW'o witnesses.

JAMES B. PIERCE, Jn.

VVitnesses': u

HENRY WALKER, HUGH G. NICHOLSON.-

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

